I will admit, I have never seen an interpretation of Rei Ayanami with long hair before - which is quite odd. The look does suit her enigmatic nature and adds to her appeal with a certain degree of maturity. The shading of the colors is fairly balanced and with her body not overly-exaggerated in improbable portions is a positive plus. Even without a background, this fan art is impressive.
I will add this delightful piece into my Beautiful Women collection. Hope you are pleased with my comment.